Indoor Pass-by Noise Testing
In recent years, many vehicle manufacturers (and some of their sub-suppliers) have set up large semi-anechoic chambers with chassis dynamometers, where the vehicle can be loaded and operated and its interior and exterior noise measured.
With reduced influence of ambient weather conditions and site variations, measurements are more reproducible and with a stationary vehicle, a greater degree of instrumentation is possible.
In such facilities, simulation of a Pass-by noise test is possible with the PULSE Indoor Pass-by Noise Test software.
Instead of making the test vehicle pass two stationary microphones as is standard in a Passby measurement, Indoor Pass-by measurements place a row of microphones alongside the test vehicle. The vehicle is running on the chassis dynamometer and accelerated in the same way as it would be for a Vehicle Pass-by measurement.
Simultaneous recordings of vehicle exterior noise at all microphone positions, operating condition signals from the dynamometer and any additional vehicle parameters are taken.
By extracting sections of the time history from the appropriate microphones and stitching them together, it is possible to create a single time history, which reproduces the effect of the vehicle passing two microphones. This single time record combined with the dynamometer drum speed profile represents the vehicle noise emitted during a Pass-by measurement.
This time history is then played back through the analysis section of the system to obtain the Pass-by results.
Furthermore ISO has started to discuss the Indoor Pass-by as a conformance test in ISO 362. The Indoor Pass-by Noise measurement would be the standard measurement together with Field Pass-by.
Features
- SPC-environment user Interface
- Simulation of Vehicle Pass-by Noise Test in hemi-anechoic rooms for product development and troubleshooting
- To provide a high degree of flexibility, analysis is performed on virtual pass-by time histories that are synthesised from the individual recorded signals
- Suitable for measurement in limited spaces where microphones cannot be positioned at the recommended 7.5 metres from the vehicle centre. The amplitudes of the microphone signals are corrected by assuming that noise comes from one point on each side (left and right acoustical centres), independent of frequency
- New calculations for different acoustic centre positions can be obtained from the same set of recordings to improve the match between Indoor and Field Pass-by results
- Microphone time histories, virtual time histories and analysis results can be separately stored in the database. They can be retrieved at any time and reprocessed with different calculation setups
- Complete management of constraints for validation according to predefined and user-definable constraint tables
- Support for tyre noise correction allowing users to replace tyre noise from Indoor test with tyre noise data recorded on the test track for more realistic total vehicle noise
- Exterior Noise Contribution Analysis is available as an option
